Histological picture of video-assisted thoracoscopic surgery lung biopsy sample. Haematoxylin and eosin stain. The specimens from the right lower and middle lung lobes show preservation of the lung architecture with patchy distribution of intra-alveolar fibrin, in the form of fibrin "balls" (insert a), associated with organizing pneumonia, consisting of intraluminal loose connective tissue within the alveolar ducts and bronchioles (insert b). Hyaline membranes, vascular thrombi or eosinophils are absent. The intervening lung parenchyma between the affected areas shows minimal changes, such as a sparse inflammatory infiltrate or minimal interstitial thickening.